Such inhalation devices are provided with a chamber for containing a pharmaceutical composition, and are configured in such a way that outside air is introduced to the chamber by the inhalation-induced pressure of a user (patient) to apply an air-generated impact to the pharmaceutical composition, thus pulverizing the pharmaceutical composition into fine particles so that the user (patient) can inhale the pulverized pharmaceutical composition into the lungs from the mouth-side flow path (disclosed in Japanese Unexamined Patent Application No. 1999-221280, for example).
Such an inhalation device disadvantageously places a burden on users (patients) who have reduced pulmonary capacity or children (patients) when generating the air impact with his/her inhalation-induced pressure.
This burden on the user can be reduced by providing an auxiliary flow path which directly reaches the mouth-side flow path of the mouthpiece, not via the chamber, so that he/she can inhale outside air which is not used for applying air impact to the pharmaceutical composition (hereinafter, referred to as auxiliary air). This auxiliary air also serves to efficiently deliver the generated fine particles to the lungs.
However, because fine particles easily coalesce/agglomerate, they tend to form coalesced or agglomerated masses due to disturbances in the air flow within the mouth-side flow path of the mouthpiece that are caused when the auxiliary air is mixed with air containing the pulverized pharmaceutical composition. Thus, some of the pulverized pharmaceutical composition does not reach the user's (patient's) lungs and adheres to his/her throat.
The pulverized pharmaceutical composition is partially dispersed in the form of agglomerated masses of fine particles when the air-generated impact applied to the pharmaceutical composition is insufficient.
In view of the above-described problems, the present invention provides an inhalation device for transpulmonary administration which can prevent agglomerated masses of fine particles of the pharmaceutical composition from entering the user's (patient's) mouth.